Watch: How Europe is greener now than 100 years ago

Within the last 100 years, Europe has experienced two World Wars, the end of communism, the emergence of the European Union and a series of other transformative political and economic developments. A team of scientists has now been able to visualize the impact of historical events in maps that show the growth and decline of settlements, forests and croplands.

The map, shown above, is the result of a research project led by Dutch scholar Richard Fuchs from the University of Wageningen. Besides regional political and economic trends, Europe's landscape was shaped by several larger developments of the 20th century, according to Fuchs.

The following maps preview some of the affected regions which we will explain and show in detail throughout this post.

"More than 100 years ago, timber was used for almost everything: as fuel wood, for metal production, furniture, house construction. Hence, at around 1900 there was hardly any forest areas left in Europe. Especially after World War II, many countries started massive afforestation programs which are still running today," Fuchs told The Washington Post.

As a result, Europe's forests grew by a third over the last 100 years. At the same time, cropland decreased due to technological innovations such as motorization, better drainage and irrigation systems: Relatively fewer area was needed to produce the same amount of food. Furthermore, many people migrated from rural to urban areas, or overseas.

Fuchs' fascinating conclusion: Forests and settlements grew at the same time and Europe is a much greener continent today than it was 100 years ago. A closer look at different regions and countries reveals Europe's recovery from the deforestation of past centuries.

In France, Spain and Italy, reforestation was particularly visible

In the southern French region of Vaucluse, entire mountain ranges were de-forested at the beginning of the 20th century, but the country invested heavily to reverse the trend. Meanwhile, agricultural projects in southern Spain transformed once arid, barren areas into profitable agricultural fields or even forests.

A similar development was documented in Italy. Former cropland were abandoned due to market competition, urbanization and emigration. Today, many parts of the Apennine Mountains (located on the right side of the map below) are dominated by grasslands and forests again.

The end of communism also led to forest growth in eastern Europe

In eastern Europe, many forests re-grew after the end of the Soviet Union. Fuchs and his colleagues explain the development with the fact that many privatized agricultural farms were less competitive on the global market. Therefore, farmers abandoned unprofitable cropland. Particularly in Romania and Poland, former cropland was taken back by nature afterward, first turning into grassland and later into forests.

In the 1990s, Europe also introduced a Common Agricultural Policy which stated that only highly productive areas should be used as cropland, in order to prevent inefficiency. Hence, fields got continuously bigger to better manage and maintain them with machines. Marginal land, however, was given up.

Scandinavian forests recovered to supply other countries

To the north of formerly communist Estonia, Latvia and Lithuania, Scandinavian countries were able to re-grow most of their forests (and are continuing to do so today) to keep up with timer demand, as they substituted most other suppliers in Europe that had practically used up most of their own wood resources.

Elsewhere, re-forestation programs soon had a visible impact, as well...

... as more and more people moved into urban areas

What you see here is among of the most populous areas of Europe: London (the growing, red area in the upper part of the picture), Paris (lower left side), and Brussels (in the middle). Although London experienced its most significant population growth in the 19th century, the city's suburbs grew massively in the 20th century and continue to do so.

The city of Paris itself actually lost inhabitants over the 20th century due to gentrification and higher rents, but you can clearly see how its suburbs became more and more populous throughout the century.

Britain recovered from excessive timber demand, as the Netherlands expanded its forests

Both the Netherlands and Britain had empires that relied heavily on the sea and their naval strength. In order to build ships, they needed wood -- and in 1900, only 2 - 3 percent of their territory was still covered with forests. Both countries have since been able to increase their forest area to 10-12 percent, as data from 2010 shows. The Netherlands also pursued another major project, visible on maps: It reclaimed the Zuiderzee bay with dams and drainage systems to gain more land.

A closer look at England and Ireland shows that both countries are nevertheless still mainly covered with grassland, while re-forestation has been particularly successful in Scotland.